Dosing & Uses
Dosage Forms & Strengths
injectable solution
- 10mg/mL
- 40mg/mL
Intravenous solution
- 60mg (50mL)
- 70mg (50mL)
- 80mg (50mL, 100mL)
- 90mg (100mL)
- 100mg (50mL, 100mL)
- 120mg (100mL)
In underweight and nonobese patients, use of total body weight (TBW) instead of ideal body weight for determining initial mg/kg/dose is accepted; ideal body weight (IBW) also may be used to determine doses for patients who are neither underweight nor obese
Susceptible Infections
Extended dosing interval
- Initial: 5-7 mg/kg/dose IV qDay
- Not for use in patients with ascites, burns covering >20% of total body surface area, cystic fibrosis, end-stage renal disease, endocarditis, infants, mycobacterial infections, or pregnancy
- Measure gentamicin level between 6 and 14 hr after initiating gentamicin infusion; use institution-specific nomogram to determine appropriate dosing interval
Surgical Prophylaxis (Off-label)
5 mg/kg IV as single dose 1 hr prior to surgical incision; alternativley, 1.5 mg/kg IV as single dose for gynecology procedures
Dose is based on actual body weight (TBW) unless body weight is >20% above ideal body weight (IBW), in which case the dosing weight can be estimated by IBW + 0.4 (TBW - IBW)
Infective Endocarditis Treatment
Enterococcus (native or prosthetic valve); Off-label dose
S. aureus (prosthetic valve; methicillin susceptible or resistant); Off-label dose
Viridans group streptococcus and S. bovis (native or prosthetic valve); Off-label use
- 3 mg/kg/day IV/IM qDay (preferred) or divided q8hr for 2 weeks for native or prosthetic valve infections or for 6 weeks for prosthetic valve infections with relatively or fully resistant strains in combination with other antibiotic
- Organism sensitivity testing and source of infection should determine choice of concomitant antibiotic
Pelvic Inflammatory Disease (Off-label)
Loading dose: 2 mg/kg IV or IM
Maintenance dose: 1.5 mg/kg IV/IM q8hr plus clindamycin IV or 3-5 mg/kg IV qDay
May initiate transition from parenteral to oral therapy of either oral doxycycline or oral clindamycin within 24-48 hr of clinical improvement for total treatment duration of 14 days
Plague (Yersinia pestis) Treatment; Off-label use
5 mg/kg IV/IM qDay for 10 days or 2 mg/kg IV/IM loading dose; then 1.7 mg/kg/dose IV/IM q8hr for 10-14 days or until 2 days after patient is afebrile; doxycycline, ciprofloxacin, or chloramphenicol could be used as third-line alternatives
Mycobacterium Infection (Orphan)
Gentamicin liposome injection: For disseminated Mycobacterium avium-intracellulare infection
Orphan indication sponsor
- Liposome Company, Inc; One Research Way; Princeton, NJ 08540
Dosing Considerations
Gentamicin may be administered IV/IM
Infuse over 30-120 min when administering IV
Dosing regimens are numerous and are adjusted based on CrCl and changes in volume of distribution, as well as on the body space where distribution of the agent will occur
Monitor peak (4-12 mg/L) and trough (1-2 mg/L)
Monitor nephrotoxicity, neurotoxicity, and ototoxicity; assess at beginning of therapy and throughout
Each regimen must be followed by at least trough level drawn on third or fourth dose, 30 min before dosing unless renal toxicity suspected
May draw peak level 30 min after 30-min infusion has been completed or 1 hr after IM injection
Use ideal body weight for mg/kg/dose; more accurate than total body weight
Gentamicin is usually a first-line aminoglycoside against infections with gram-negative organisms such as Pseudomonas aeruginosa, Proteus, Escherichia coli, Klebsiella, Enterobacter, Serratia, and Citrobacter, as well as against Staphylococcus (gram- positive)
Bacterial organisms causing susceptible infections
- Susceptible infections include the following:
- Pseudomonas aeruginosa
- Proteus species (indole-positive and indole-negative)
- Escherichia coli
- Klebsiella-Enterobacter-Serratia species
- Citrobacter species
- Staphylococcus species (coagulase-positive and coagulase-negative)
- Pseudomonas aeruginosa
- Proteus species (indole-positive and indole-negative)
- Escherichia coli
- Klebsiella-Enterobacter-Serratia species
- Citrobacter species
- Staphylococcus species (coagulase-positive and coagulase-negative)
Dosing Modifications
Renal impairment
Conventional dosing
Once daily (interval adjustment of extended interval dosing)
Intermittent hemodialysis
- Administer after hemodialysis on dialysis days
- Dependent on patients size, site of injection, filter, duration and type of intermittent hemodialysis, it is ~30-50% dialyzable
- 1-1.7 mg/kg IV/IM after initial hemodialysis session; serum gentamicin concentrations should guide subsequent dosing
- Dosing dependent on assumption of 3 times/wk complete intermittent hemodialysis sessions
Peritoneal dialysis
- Intermittent dosing: 0.6 mg/kg per exchange once daily for anuric patients; 0.75 mg/kg/dose IP for non-anuric patients qDay during long dwell periods; depending on infecting organism and patient's clinical status, may treat for 2-3 weeks
- Continuous dosing: 8 mg/L loading dose; followed by 4 mg/L maintenance dose
Continuous renal replacement therapy
- Drug clearance is highly dependent on method of renal replacement, filter type, and flow rate; close monitoring of pharmacologic response, sign of adverse reactions due to accumulation, and target drug concentration necessary for appropriate dosing
- 3 mg/kg/day IV/IM divided q8hr; may administer up to 5 mg/kg/day IV/IM divided q6-8hr in life-threatening infections; peak; adjust dose based on serum concentration monitoring; peak concentration >12 mcg/mL should be avoided
Dosage Forms & Strengths
injectable solution
- 10mg/mL
- 40mg/mL
Intravenous solution
- Intravenous solution
- 60mg (50mL)
- 70mg (50mL)
- 80mg (50mL, 100mL)
- 90mg (100mL)
- 100mg (50mL, 100mL)
- 120mg (100mL)
Use of ideal body weight (IBW) for determining the mg/kg/dose appears to be more accurate than on the basis of total body weight (TBW)
Susceptible Infections
Infants: 2.5 mg/kg/dose IV/IM q8hr
Surgical Prophylaxis, Preoperative (Off-label use)
2.5 mg/kg IV/IM within 60 min piror to surgical incision or without antibiotics; procedure dependent
Dose is based on actual body weight unless >20% above ideal body weight; then dosage requirement may best be estimated using a dosing weight of IBW + 0.4 (TBW- IBW)
Dosing Considerations
Monitor peak (4-12 mg/L) and trough (1-2 mg/L)
Monitor nephrotoxicity, neurotoxicity, and ototoxicity; assess at beginning of therapy and throughout
Individualization critical due to low therapeutic index
Use ideal body weight for mg/kg/dose, except in neonates (in whom actual body weight should be used)
Bacterial organisms causing susceptible infections
- Pseudomonas aeruginosa
- Proteus species (indole-positive and indole-negative)
- Escherichia coli
- Klebsiella-Enterobacter-Serratia species
- Citrobacter species
- Staphylococcus species (coagulase-positive and coagulase-negative)
Dosing Modifications
GFR>50 mL/min/1.73m²: No dosage adjustment necessary
GFR 30-50 mL/min/1.73m²: Administer q12-18hr
GFR 10-29 mL/min/1.73m²: Administer q18-24hr
GFR <10 mL/min/1.73m² Administer q48-72hr
Intermitent hemodialysis: 2 mg/kg/dose; redose as indicated by serum concentration
Peritoneal dialysis: 2 mg/kg/dose; redose as indicated by serum concentration
Continuous renal replacement therapy: 2-2.5 mg/kg/dose q12-24hr; monitor serum concentration
Interactions
Interaction Checker
No Results
Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor
Adverse Effects
>10%
Neurotoxicity (vertigo, ataxia)
Gait instability
Ototoxicity (auditory, vestibular)
Nephrotoxicity (decreased CrCl)
Nephrotoxicity if trough >2 mg/L
1-10%
Edema
Rash
Reddening of skin
Itching
<1%
Drowsiness
Headache
Pseudomotor cerebri
Photosensitivity
Allergic reaction
Erythema
Anorexia
Nausea/vomiting
Weight loss
Increased salivation
Enterocolitis
Granulocytopenia
Agranulocytosis
Thrombocytopenia
Elevated LFTs
Burning
Stinging
Tremors
Muscle cramps
Weakness
Dyspnea
Warnings
Black Box Warnings
Patients treated with aminoglycosides should be under close clinical observation due to potential toxicity associated with their use
Neurotoxicity, manifested as bilateral auditory and vestibular ototoxicity, can occur in patients with preexisting renal impairment and in patients with normal renal function treated at higher doses and/or for periods longer than those recommended; high-frequency deafness usually occurs first and can be detected only with audiometric testing
Aminoglycosides are potentially nephrotoxic; risk is greater in patients with impaired renal function and in those who receive high doses or prolonged therapy; rarely, nephrotoxicity may not become apparent until the first few days after cessation of therapy
Use with caution in premature infants and neonates because of renal immaturity and the resulting prolongation of serum half-life of the drug
Monitor eighth cranial nerve and renal function; especially in patients with known or suspected reduced renal function at onset of therapy and also in patients with normal function at the beginning of therpay but that develop signs of rena dysfunction during therapy; examine urine for increased excretion of protein, decreased specific gravity and presence of cells; serial audiograms should be obtained when possible; adjust the dose or discontinue therapy if there is evidence of ototoxicity or nephrtoxicity
Neuromuscular blockade and respiratory paralysis have been reported following parenteral injection, topical instillation (as in orthopedic and abdominal irrigation or in local treatment of empyema), and oral use of aminoglycosides, especially when given soon after anesthesia or muscle relaxants; if blockage occurs, calcium salts may reverse these phenomena, but mechanical respiratory assistance may be necessary
Avoid concurrent or sequential use of neurotoxic and/or nephrotoxic drugs, including other aminoglycosides (eg, amikacin, streptomycin, neomycin, kanamycin, paromomycin)
Cumulative listing of drugs to avoid from all aminoglycosides; package inserts includes amphotericin B, bacitracin, cephaloridine, cisplatin, colistin, polymyxin B, vancomycin, and viomycin
Avoid potent diuretics (eg, ethacrynic acid, furosemide) because they increase risk of ototoxicity; when administered intravenously, diuretics may enhance aminoglycoside toxicity by altering antibiotic concentrations in serum and tissue
Contraindications
Prior aminoglycoside toxicity or hypersensitivity
Cautions
Patients treated withaminoglycosides should be under close clinical observation; high risk of toxicity associated with their use
Risk of ototoxicity; tinnitus or vertigo may be indications of vestibular injury and impending bilateral irreversible damage; discontinue therapy if signs of ototoxicity occur
Risk of nephrotoxicity; other factors that increase patient risk of ototoxicity include advanced age and dehydration
Narrow therapeutic index (not intended for long-term therapy)
Caution in renal failure (not on dialysis), myasthenia gravis, hypocalcemia, and conditions that depress neuromuscular transmission
Adjust dose in renal impairment
Endocarditis prophylaxis (GI, GU procedure): AHA Guidelines recommend only for high-risk patients
Diuretics may enhance aminoglycoside toxicity by altering antibiotic concentration in serum and tissue; certain diuretics by themselves may cause ototoxicity; avoid potent diuretics, including ethacrynic acid or furosemide
Use caution in patients with electrolyte abnormalitie including hypocalcemia, hypomagnesemia, or hypokelemia
Use caution in patients with neuromuscular disorders, including myasthenia gravis
Use caution in patients with hearing and renal impairment
Pregnancy & Lactation
Pregnancy category: D
Lactation: Enters breast milk; use with caution (AAP Committee states "compatible with nursing")
Pregnancy Categories
A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA:Information not available.
Pharmacology
Mechanism of Action
Aminoglycoside antibiotic for coverage of gram-negative bacteria, including Pseudomonas species; synergistic with beta lactamase against enterococci; interferes with bacterial protein synthesis by binding to 30S and 50S ribosomal subunits
Absorption
Peak plasma time: IM (30-90 min); IV (30 min after 30-min infusion)
Distribution
Gentamicin crosses placenta; relative diffusion from blood into CSF is minimal even with inflammation
CSF-to-blood level ratio: Normal meninges (minimal); inflamed meninges (10-30%)
Protein bound: <30%
Vd: Neonates (0.4-0.6 L/kg); children: (0.3-0.35 L/kg); adults: (0.2-0.3 L/kg); Vd increased by edema, ascites, and fluid overload and decreased by dehydration
Elimination
Half-life: 2-3 hr (NRF)
Renal clearance: Directly related to renal function
Excretion: Urine (70% recovered as unchanged drug in patients with NRF)
Administration
IV Incompatibilities
Additive: Ampho B, ampicillin, cefazolin, dopamine, furosemide, heparin
Syringe: Ampicillin, heparin
Y-site: Furosemide, heparin
Not spec: Carbenicillin
IV Compatibilities
Additive: cimetidine, clindamycin, verapamil
Syringe: clindamycin
Y-site: Amiodarone, esmolol, vitamins B/C
IV Preparation
Dilute single dose in 50-200 mL NS or D5W
IV Administration
Infuse over 30 min-2 hr
After infusion, flush line with NS or D5W
Images
Patient Handout
Formulary
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